Quick Answer
A 25-year warranty is a good starting point but may not be enough to guarantee the longevity of solar panels, as degradation rates can vary greatly depending on factors such as temperature, humidity, and panel quality.
Understanding Solar Panel Degradation
Solar panel degradation refers to the loss of efficiency over time, typically measured as a percentage of initial power output. Most high-quality panels degrade at a rate of 0.5-1% per year, while some premium panels may degrade at a rate as low as 0.2% per year. However, temperatures above 25°C (77°F) can accelerate degradation, with some studies showing a 10-20% increase in degradation for every 10°C (18°F) above this threshold.
Assessing Warranty Length and Degradation
A 25-year warranty may seem impressive, but it’s essential to consider the actual expected lifespan of the panels. Assuming an average degradation rate of 0.7% per year, a solar panel’s efficiency would decrease by around 17% over 25 years. This means that while the panel may still produce power, its efficiency will be significantly reduced. In contrast, a premium panel with a 0.3% degradation rate would only lose around 7% of its efficiency over the same period. When evaluating warranty length, it’s crucial to consider the quality of the panels and the expected degradation rate.
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